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go spec: modification of defer statement
R=r, rsc, ken2, iant CC=golang-dev https://golang.org/cl/708041
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@ -2996,8 +2996,6 @@ which must be <i>addressable</i>,
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that is, either a variable, pointer indirection, array or slice indexing
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operation,
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or a field selector of an addressable struct operand.
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A function result variable is not addressable.
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<!--- (<span class="alert">TODO: remove this restriction.</span>) --->
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Given an operand of pointer type, the pointer indirection
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operator <code>*</code> retrieves the value pointed
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to by the operand.
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@ -4281,7 +4279,12 @@ executes, the parameters to the function call are evaluated and saved anew but t
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function is not invoked.
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Deferred function calls are executed in LIFO order
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immediately before the surrounding function returns,
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but after the return values, if any, have been evaluated.
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after the return values, if any, have been evaluated, but before they
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are returned to the caller. For instance, if the deferred function is
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a <a href="#Function_literals">function literal<a/> and the surrounding
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function has <a href="#Function_types">named result parameters</a> that
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are in scope within the literal, the deferred function may access and modify
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the result parameters before they are returned.
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</p>
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<pre>
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@ -4292,6 +4295,14 @@ defer unlock(l) // unlocking happens before surrounding function returns
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for i := 0; i <= 3; i++ {
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defer fmt.Print(i)
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}
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// f returns 1
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func f() (result int) {
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defer func() {
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result++
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}()
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return 0
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}
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</pre>
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<h2 id="Built-in_functions">Built-in functions</h2>
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@ -4928,7 +4939,8 @@ The following minimal alignment properties are guaranteed:
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<h2 id="Implementation_differences"><span class="alert">Implementation differences - TODO</span></h2>
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<ul>
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<li><span class="alert">Implementation does not honor the restriction on goto statements and targets (no intervening declarations).</span></li>
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<li><span class="alert">Method expressions are not implemented.</span></li>
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<li><span class="alert">The implementation of complex numbers is incomplete.</span></li>
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<li><span class="alert">Method expressions are partially implemented.</span></li>
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<li><span class="alert">Gccgo allows only one init() function per source file.</span></li>
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<li><span class="alert">Deferred functions cannot access the surrounding function's result parameters.</span></li>
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<li><span class="alert">Function results are not addressable.</span></li>
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</ul>
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